that confirmed serious risks specifically associated with the drug, Vioxx, which Merck had withdrawn from the market two years earlier, in 2004, and which argued that Merck should have known about the risks. He participated in the Global Burden of Disease Study, funded by the Bill & Melinda Gates Foundation. He founded Toxin Alert, as a public alert tool to warn communities about drinking water contaminations to prevent future lead poisonings like the Flint Water Crisis. Coronavirus preparedness advocacy On January 20, 2020, Feigl-Ding went viral on Twitter after expressing his worries about the 2019–20 Wuhan coronavirus outbreak virus' basic reproduction number (R0) of up to 3.8. He compared the virus pandemic potential to the 1918 influenza pandemic which has an estimated R0 of 1.8 and which killed ~50 million people out of 2 billion, and called for WHO and CDC to preemptively declare public health emergency and monitor aggressively the situation. With the thread going viral, his appeals were criticized by some epidemiologist peers as alarmist and based on anecdotal data, by some journalists as misleading and misinforming the public, while defended by other journalists, and other epidemiologist peers, such as his former Harvard adviser Simin Liu, a Harvard School of Public Health and Brown University School of Public Health professor of epidemiology. While Feigl-Ding deleted his earliest tweets, the rapid development of the epidemic, first in China in January, then in Europe in February–March and in the United States in March, together with more studies on the virus, turned his perceptions into that of an early messenger, and he was invited as a commentator on the pandemic by news media. An earlier Atlantic article by Alexis Madrigal was self-admitted by Madrigal to be due for a re-assessment after his realization of the pandemic and reading of the assessment by David Wallace-Wells. Madrigal admitted that his earlier "...piece made sense on Planet A, where a pandemic was not bearing down on us, but not on Planet B, where we all now live. It was right in the particulars and wrong on the big picture." Controversies concerning epidemiological expertise and accuracy Feigl-Ding holds doctorates in both epidemiology and nutrition, with his professional experience in nutritional epidemiology and epidemiology of chronic disease. Prior to the COVID-19 pandemic, his research work and expertise primarily focused on the health effects of diet and exercise, he also lacked academic publication in infectious disease epidemiology,